"Warm weather in Rajasthan adversely impacted the overall sowing of mustard seed and acreage fell nearly 26 per cent to 2.05 million hectare and any improvement is unlikely now," a senior official of agriculture ministry said.

Rajasthan is the largest mustard seed producing state and last year area under the seed stood at 2.77 million hectares and for this year the state government set a target of 2.8 million hectare. Normally, southwest monsoon starts withdrawing from Rajasthan by early September but in 2017 it was delayed though rain remained weak in the state.

Mustard seed is the major rabi oilseed crop and generally sown during October-November. In Uttar Pradesh, the sowing stood at1.21 million hectare a year ago. It is the second largest mustard seed producing state. Mustard sowing in Madhya Pradesh improved to 750,000 hectare from 700,000 hectare a year ago. Sowing under mustard seed also increased in Assam, Gujarat, Bihar, West Bengal and Jharkhand.